when a player is "flying" with fly disabled, the fly disconnection chat message results in this error: "Connection Lost - Internal Exception: io.netty.handler.codec.DecoderException: Java.lang.UnsupportedOperationException: JsonObject"

Flying is only one concrete example of how Json chats appear to be causing this error. I only found this specific concrete example with flying because I used a server wrapper in proxy mode that created a fake block for the client to stand on (one that did not exist on the server end).

I suspect this error also causes problems with other packets that use Json as well and is causing plenty of spurious disconnections when in the vacinity of other players. I can only prove this specific instance.